LLVM Weekly - #61, Mar 2nd 2015

Welcome to the sixty-first issue of LLVM Weekly, a weekly newsletter
(published every Monday) covering developments in LLVM, Clang, and related
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On the mailing lists

Ashutosh Nema is proposing a new loop versioning
optimisation.
This is where multiple versions of the loop are generated and the
implementation chosen based on runtime memory aliasing tests. It was suggested
that some recent work on Loop Access Analysis provides some of this
functionality.

Ahmed Bougacha started a discussion on disabling
GlobalMerge,
which is currently enabled for ARM and AARch64. Much of the ensuing discussion
centers around understanding why there seems to be a performance degradation
when using GlobalMerge with LTO.

Katya Romanova moved a discussion on a jump threading optimisation
bug to
llvm-dev. The issue is due to the fact an unreachable block is generated with
ill-formed instruction, and there is a lot of follow on discussion about
whether passes should generate unreachable blocks.